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| Home > Publications database > Verfahren zur Bestimmung von Spurenelementen in Wasserproben mit der Neutronenaktivierungsanalyse : Abschlussbericht |
| Home > Publications database > Verfahren zur Bestimmung von Spurenelementen in Wasserproben mit der Neutronenaktivierungsanalyse : Abschlussbericht |
| Book/Report | FZJ-2018-01585 |
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1981
Kernforschungsanlage Jülich, Verlag
Jülich
Please use a persistent id in citations: http://hdl.handle.net/2128/17549
Report No.: Juel-1716
Abstract: For the determination of trace elements in wate.r by neutron activation analysis irradiation procedures and themical separation procedures have been developed. The irradiation in a nuclear reactor should be done without special sample preparation to avoid introduction or losses of trace elements from or to chemicals and vessels.The following irradiation procedures have been investigated: 1) Irradiation in open cuvettes made from silica with a volume of up to 170 ml at a neutron flux of 3·10$^{13}$ n cm$^{-2}$ sec$^{-1}$. The gases oxygen and hydrogen, which are produced by radiolysis, are drawn off by the reactor spent air system. This irradiation device was very fragile und therefore not suitable. 2} Irradiation in open flasks made from silica with a volume of about 50 ml at a neutron flux of 8 · 10$^{13}$n cm$^{-2}$sec$^{-1}$. The gases produced by radiolysis are collected in an aluminium container seizing 200 ml. In this irradiation device water samples up to 40 ml could be irradiated for up to two hours. 3) Irradiation in polyethylene flasks with screw caps with a volume of 125 ml at a neutron flux of 8·10$^{13}$n cm$^{-2}$sec$^{-1}$. 40 ml samples could be irradiated for about 10 mine At longer exposure times the polyethylene became brittly. 4) Irradiation in sealed silica ampoules with a volume of about 15 ml at a neutron flux of 8·10$^{13}$n cm$^{-2}$sec$^{-1}$. 5-ml-samples could be irradiated for about 1 hour. After longer irradiation times the ampoules bursted sometimes when they were to be opened. Therefore this procedure was unsuitable. 5} Irradiation as with 4), but in the presence of a small platinum wire which recombines the oxyhydrogengas produced by radiolysis. Samples of 5 ml could be irradiated for 15 hours without any increase of pressure to be observed in the ampoules. Procedures for cleaning the vessels for sample storage and irradiation have been studied by tracer methods. Blind values caused by introduction of trace constituents of the vessel materials have been measured. Losses of trace elements from the samples due to adsorption at the vessel walls and the consequent errors in the analytical results have been investigated. The irradiated samples can be measured directly with a gamma ray spectrometer and from the radionuclides found the trace element contents may be calculated. More sensitive determinations are possible if the radionuclides are chemically separated. Procedures for removing the matrix activities, for the separation of the radionuclides in groups of elements and for the isolation of single elements have been developed. The group separation is carried out in a small automatical apparatus consisting of a filter, a column of hydrated antimony pentoxide (HAP) , a column of AG 1x8-resin, a pump and the containers for the sample and the elution agent. The sample is made up to 7n HCl adding conc. HCl and pumped through the columns. The filter removes the suspended matter, the HAP-column absorbs the Na. The anion exchanger, which is in the chloride form, is passed by the ions of K, Sc, er, Mn, Ag, La and Ce which have no or only weak chloro complexes. In a second step 1n HCl is pumped over the anion exchange column and the elements adsorbedon the column are separated in two groups. Fe, Cu, Ga and W are eluted while the strong chloro complexes of Zn, Cd, Sb and Hg remain on the column. The separation procedure has been checked for the chemical yields and the reproducibility of the results has been determined. For especially sensitive determinations of some elements selective separation procedures for antimony, cadmium, selenium, mercury and uranium have been developed. The analytical procedures described have been applied to trace element determinations in river water, glacier ice and water solutions from technical processes.
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